Lei Yan, PhD
Associate Research Scientist in BiostatisticsDownloadHi-Res Photo
Cards
Contact Info
About
Copy Link
Titles
Associate Research Scientist in Biostatistics
Biography
I am an Associate Research Scientist in Biostatistics at Yale Public Health.
My research focuses on the application of advanced causal inference methods to questions in comparative effectiveness research, utilizing large electronic health records and other observational data to enhance health decision-making. Ongoing projects include estimating the causal effects of pharmacotherapies on the short- and long-term risk of COVID-19, examining the use of antidepressants and their effects on individuals with major depression, evaluating the effectiveness of respiratory syncytial virus vaccines, assessing the efficacy and duration of dolutegravir-based regimens for individuals with HIV, and investigating gene-environment interactions in the development of childhood acute lymphoblastic leukemia. These projects are conducted collaboratively with faculty and researchers at Yale Public Health and the Clinical Epidemiology Research Center (CERC) at the VA Connecticut Healthcare System located in West Haven. My previous research focused on the financialization of commodity markets.
Last Updated on January 20, 2024.
Appointments
Biostatistics
Associate Research ScientistPrimary
Other Departments & Organizations
Education & Training
- Postdoctoral Research Associate
- University of Illinois at Urbana-Champaign (2018)
- PhD
- University of Illinois at Urbana-Champaign, Applied Economics (2017)
- MA
- Renmin University of China, Economics (2011)
- BS
- Renmin University of China, Statistics (2008)
Research
Copy Link
Overview
Medical Research Interests
Data Science
Public Health Interests
Pharmacoepidemiology; Survival Analysis; HIV/AIDS; Epidemiology Methods
ORCID
0000-0002-4779-2688
Publications
Featured Publications
Respiratory syncytial virus vaccine effectiveness among US veterans, September, 2023 to March, 2024: a target trial emulation study
Bajema K, Yan L, Li Y, Argraves S, Rajeevan N, Fox A, Vergun R, Berry K, Bui D, Huang Y, Lin H, Hynes D, Lucero-Obusan C, Schirmer P, Cunningham F, Huang G, Aslan M, Ioannou G. Respiratory syncytial virus vaccine effectiveness among US veterans, September, 2023 to March, 2024: a target trial emulation study. The Lancet Infectious Diseases 2025, 25: 625-633. PMID: 39848264, DOI: 10.1016/s1473-3099(24)00796-5.Peer-Reviewed Original ResearchCitationsAltmetricConceptsRespiratory syncytial virusRespiratory syncytial virus vaccinePositive RSV testVaccine effectivenessRSV testCare encountersSecondary outcomesEmergency departmentRSV-associated hospitalisationsMedian Follow-UpUS Food and Drug AdministrationHealth-care useVeterans Health AdministrationRespiratory illness seasonMatched index dateElectronic health recordsLower respiratory tract diseaseRSV-related illnessFood and Drug AdministrationDepartment of Veterans Affairs Cooperative Studies ProgramVeterans Affairs Cooperative Studies ProgramCooperative Studies ProgramRSV infectionMedian ageUS DepartmentSeverity and Long-Term Mortality of COVID-19, Influenza, and Respiratory Syncytial Virus
Bajema K, Bui D, Yan L, Li Y, Rajeevan N, Vergun R, Berry K, Huang Y, Lin H, Aslan M, Ioannou G. Severity and Long-Term Mortality of COVID-19, Influenza, and Respiratory Syncytial Virus. JAMA Internal Medicine 2025, 185: 324-334. PMID: 39869355, PMCID: PMC11773409, DOI: 10.1001/jamainternmed.2024.7452.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsRespiratory syncytial virusLong-term mortalitySARS-CoV-2Syncytial virusCohort studyAssociated with higher long-term mortalityRisk differenceIntensive care unit admissionSeasonal influenza vaccineRetrospective cohort studyDisease severity of COVID-19Long-term deathAssociated with more severe disease outcomesRisk of deathCompare disease severitySevere disease outcomesRisk of hospitalizationSeverity of COVID-19Same-day testingInfluenza vaccineInverse probability weightingUnit admissionCumulative incidenceMortality of COVID-19Primary outcomeEffectiveness of dolutegravir-based regimens compared to raltegravir-, elvitegravir-, bictegravir, and darunavir-based regimens among older adults with HIV in the Veterans Aging Cohort Study (VACS)
Yan L, Henegar C, Marconi V, Gordon K, Hicks C, Vannappagari V, Justice A, Aslan M. Effectiveness of dolutegravir-based regimens compared to raltegravir-, elvitegravir-, bictegravir, and darunavir-based regimens among older adults with HIV in the Veterans Aging Cohort Study (VACS). AIDS Research And Therapy 2024, 21: 96. PMID: 39709467, PMCID: PMC11662819, DOI: 10.1186/s12981-024-00681-w.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsMeSH KeywordsAgedAmidesAnti-HIV AgentsCohort StudiesDarunavirDrug Therapy, CombinationFemaleHeterocyclic Compounds, 3-RingHeterocyclic Compounds, 4 or More RingsHIV InfectionsHIV Integrase InhibitorsHumansMaleMiddle AgedOxazinesPiperazinesPyridazinesPyridonesQuinolonesRaltegravir PotassiumTreatment OutcomeVeteransViral LoadConceptsVeterans Aging Cohort StudyRAL-based regimenAntiretroviral therapyAging Cohort StudyCohort studyOdds of virologic suppressionIntegrase strand transfer inhibitorsDarunavir-based regimensDolutegravir-based regimensDTG-based regimensAntiretroviral therapy experienceHuman immunodeficiency virusDTG-based regimenInverse probability of treatment weightingStrand transfer inhibitorsBackgroundReal-world dataProbability of treatment weightingMethodsThis cohort studyVirologic suppressionVirological failureVirological effectImmunodeficiency virusDarunavir/ritonavirClinical outcomesRegimen initiationIdentifying Veterans Who Benefit From Nirmatrelvir-Ritonavir: A Target Trial Emulation
Yan L, Bui D, Li Y, Rajeevan N, Rowneki M, Berry K, Argraves S, Huang Y, Hynes D, Cunningham F, Huang G, Aslan M, Ioannou G, Bajema K. Identifying Veterans Who Benefit From Nirmatrelvir-Ritonavir: A Target Trial Emulation. Clinical Infectious Diseases 2024, 79: 643-651. PMID: 38864601, DOI: 10.1093/cid/ciae202.Peer-Reviewed Original ResearchCitationsAltmetricConceptsRisk quartileVeterans Health AdministrationLowest risk quartileHighest risk quartileTarget trial emulationRisk prediction modelUntreated veteransRisk of deathOlder veteransYounger veteransHealth AdministrationTrial emulationMeasure IncidenceNirmatrelvir-ritonavirVeteransHospitalUntreated participantsCOVID-19QuartileRiskSevere coronavirus disease 2019ParticipantsPersonsCoronavirus disease 2019Severe COVID-19Impact of time zero designation on estimated COVID-19 antiviral effectiveness in observational studies
Bajema K, Yan L, Berry K, Bui D, Lin H, Huang Y, Li Y, Rajeevan N, Maciejewski M, Smith V, Bohnert A, Hynes D, Aslan M, Ioannou G. Impact of time zero designation on estimated COVID-19 antiviral effectiveness in observational studies. American Journal Of Epidemiology 2025, kwaf221. PMID: 41078178, DOI: 10.1093/aje/kwaf221.Peer-Reviewed Original Research
2025
Effectiveness of the 2024-2025 KP.2 COVID-19 vaccines in the United States during long-term follow-up.
Ioannou GN, Berry K, Yan L, Huang Y, Lin HM, Bui D, Hynes DM, Boyko EJ, Ferguson JM, Aslan M, Bajema KL. Effectiveness of the 2024-2025 KP.2 COVID-19 vaccines in the United States during long-term follow-up. Nat Commun 2025 PMID: 41444246, DOI: 10.1038/s41467-025-67796-0.Peer-Reviewed Original ResearchDurability of Respiratory Syncytial Virus Vaccine Effectiveness Among US Veterans
Bajema K, Bui D, Yan L, Li Y, Rajeevan N, Vergun R, Sriskantharajah V, Hynes D, Berry K, Huang Y, Lin H, Aslan M, Ioannou G. Durability of Respiratory Syncytial Virus Vaccine Effectiveness Among US Veterans. JAMA Internal Medicine 2025, 186 PMID: 41284307, PMCID: PMC12645397, DOI: 10.1001/jamainternmed.2025.6355.Peer-Reviewed Original ResearchCitationsAltmetricConceptsRespiratory syncytial virus vaccineRespiratory syncytial virusIntensive care unit admissionRSV vaccineVaccine effectivenessUnit admissionRespiratory syncytial virus illnessSevere respiratory syncytial virusVaccine doseRespiratory syncytial virus infectionMonths of follow-upLong-term effectsHealth care useRespiratory illness seasonVeterans Health AdministrationMatched index dateUrgent care visitsTarget trial emulationMedian ageCare useCare visitsSingle doseSyncytial virusIndex dateVaccine recipientsBudget Impact of Adopting Nirmatrelvir-Ritonavir for Treating COVID-19 in a Large Integrated Healthcare System
Bui D, Hynes D, Wong E, Vergun R, Yan L, Li Y, Rajeevan N, Berry K, Lin H, Huang Y, Govier D, Aslan M, Ioannou G, Bajema K. Budget Impact of Adopting Nirmatrelvir-Ritonavir for Treating COVID-19 in a Large Integrated Healthcare System. Open Forum Infectious Diseases 2025, 12: ofaf596. PMID: 41089767, PMCID: PMC12517272, DOI: 10.1093/ofid/ofaf596.Peer-Reviewed Original ResearchAltmetricConceptsVeterans Health AdministrationHealthcare systemEmergency departmentBudget impactRisk quartileIntegrated healthcare systemHealthcare utilization costsHealthcare cost savingsHighest risk quartileTarget trial emulationHealth AdministrationHealthcare costsTrial emulationHealthcareCOVID-19VeteransHospitalTargeted treatmentQuartileClinical subgroupsUtilization costsTreatment benefitTargeted treatment of patientsCost savingsTreatment of patientsTarget Trial Emulation of SARS-CoV-2 Infection Versus No Infection and Risk of Post–COVID-19 Conditions in the Omicron Variant Versus Prior Eras
Ioannou G, Berry K, Rajeevan N, Li Y, Yan L, Huang Y, Bui D, Hynes D, Rowneki M, Hickok A, Niederhausen M, Shahoumian T, Bohnert A, Boyko E, Korpak A, Fox A, Baraff A, Iwashyna T, Maciejewski M, Smith V, Berkowitz T, Pura J, Hebert P, Wong E, O’Hare A, Osborne T, Viglianti E, Aslan M, Bajema K. Target Trial Emulation of SARS-CoV-2 Infection Versus No Infection and Risk of Post–COVID-19 Conditions in the Omicron Variant Versus Prior Eras. Clinical Infectious Diseases 2025, 81: 10-19. PMID: 40208261, DOI: 10.1093/cid/ciaf087.Peer-Reviewed Original ResearchCitationsAltmetricConceptsPost-COVID-19 conditionCumulative incidence of deathVeterans Health AdministrationMatched index dateCumulative incidence differenceExcess burdenCumulative incidenceBurden of mortalityHypothetical target trialIncidence of deathDeath up to 1 yearTarget trial emulationAll-Cause MortalityHealth recordsHealth AdministrationTrial emulationIncidence differencesIndex dateUninfected participantsPost-coronavirus diseaseVeteransUnvaccinated personsTarget trialsOmicron eraVaccination statusDeconstructing fertilizer price spikes: Evidence from Chinese urea fertilizer market
Hu Z, Yan L, Yuan J, Etienne X (2025). Deconstructing fertilizer price spikes: Evidence from Chinese urea fertilizer market. Food Policy, 133.Peer-Reviewed Original Research
Academic Achievements & Community Involvement
Copy Link
Activities
activity Scientific Reports
2024 - PresentJournal ServiceEditorial Board Memberactivity Polypharmacy, Drug-Drug Interactions, and Risk of Hospitalization among Veterans with HIV Taking 2-, 3-, and 4-Drug Antiretroviral Therapy Regimens
10/19/2025 - 10/22/2025Poster PresentationIDWeek 2025DetailsWashington, DC, United StatesCollaboratorsAbstract/Synopsishttps://academic.oup.com/ofid/article/13/Supplement_1/ofaf695.447/8420596
activity Using Target Trial Emulation and Decision Tree Analyses to Assess Budget Impact and Cost Effectiveness of Nirmatrelvir-Ritonavir (NR) Allocation Strategies
06/07/2025 - 06/10/2025Poster Presentation2025 Annual Research MeetingDetailsMinneapolis, MN, United StatesCollaboratorsAbstract/Synopsishttps://academyhealth.confex.com/academyhealth/2025arm/meetingapp.cgi/Paper/70571
activity Frequency of Overlapping Prescriptions With Known Pairwise Drug Interactions Among People With HIV Taking 2-, 3- And 4-Drug Regimens in the Veterans Aging Cohort Study
10/24/2024 - 10/25/2024Oral PresentationThe 15th International Workshop on Aging & HIVDetailsWashington, DC, United StatesCollaboratorsAbstract/Synopsishttps://academicmedicaleducation.com/materials/oral-abstract-19--frequency-of-overlapping-prescriptions-with-known-pairwise-drug-interactions-among-people-with-hiv-taking-2-3-and-4-drug-regimens-in-the-veterans-aging-cohort-study--lei-yan.pdf-18851
activity Effectiveness and durability of dolutegravir/lamivudine in older people with HIV from the Veterans Aging Cohort Study (VACS)
07/22/2024 - 07/26/2024Poster PresentationThe 25th International AIDS ConferenceDetailsMunich, BY, GermanyCollaborators
Get In Touch
Copy Link
Contacts
Email
Locations
300 George Street
Academic Office
Rm 509
New Haven, CT 06511